/* Mednafen - Multi-system Emulator
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <string.h>
#include <math.h>

#include "../mednafen-types.h"
#include "../state.h"
#include "../state_helpers.h"

#include "psg.h"

void PCEFast_PSG::SetVolume(double new_volume)
{
   OutputVolume = new_volume;

   Blip_Synth_set_volume(&Synth, OutputVolume / 6, 8192);
}

void PCEFast_PSG::SetChannelUserVolume(int chnum, uint8 new_volume)
{
    if(chnum >=6 || new_volume > 100) return;  // check valid args
    psg_channel *ch = &channel[chnum];
    ch->user_volume = new_volume;
}

void PCEFast_PSG::UpdateOutput_Norm(const int32 timestamp, psg_channel *ch)
{
   int32 samp[2];
   int sv = ch->dda;

   samp[0] = dbtable[ch->vl[0]][sv];
   samp[1] = dbtable[ch->vl[1]][sv];

   Blip_Synth_offset(&Synth, timestamp, (samp[0] - ch->blip_prev_samp[0]) * ch->user_volume / 100, sbuf[0]);
   Blip_Synth_offset(&Synth, timestamp, (samp[1] - ch->blip_prev_samp[1]) * ch->user_volume / 100, sbuf[1]);

   ch->blip_prev_samp[0] = samp[0];
   ch->blip_prev_samp[1] = samp[1];
}

void PCEFast_PSG::UpdateOutput_Noise(const int32 timestamp, psg_channel *ch)
{
   int32 samp[2];
   int sv = ((ch->lfsr & 1) << 5) - (ch->lfsr & 1); //(ch->lfsr & 0x1) ? 0x1F : 0;

   samp[0] = dbtable[ch->vl[0]][sv];
   samp[1] = dbtable[ch->vl[1]][sv];

   Blip_Synth_offset(&Synth, timestamp, (samp[0] - ch->blip_prev_samp[0]) * ch->user_volume / 100, sbuf[0]);
   Blip_Synth_offset(&Synth, timestamp, (samp[1] - ch->blip_prev_samp[1]) * ch->user_volume / 100, sbuf[1]);

   ch->blip_prev_samp[0] = samp[0];
   ch->blip_prev_samp[1] = samp[1];
}

void PCEFast_PSG::UpdateOutput_Off(const int32 timestamp, psg_channel *ch)
{
   int32 samp[2];

   samp[0] = samp[1] = 0;

   Blip_Synth_offset(&Synth, timestamp, (samp[0] - ch->blip_prev_samp[0]) * ch->user_volume / 100, sbuf[0]);
   Blip_Synth_offset(&Synth, timestamp, (samp[1] - ch->blip_prev_samp[1]) * ch->user_volume / 100, sbuf[1]);

   ch->blip_prev_samp[0] = samp[0];
   ch->blip_prev_samp[1] = samp[1];
}


void PCEFast_PSG::UpdateOutput_Accum(const int32 timestamp, psg_channel *ch)
{
   int32 samp[2];

   samp[0] = ((int32)dbtable_volonly[ch->vl[0]] * ((int32)ch->samp_accum - 496)) >> (8 + 5);
   samp[1] = ((int32)dbtable_volonly[ch->vl[1]] * ((int32)ch->samp_accum - 496)) >> (8 + 5);

   Blip_Synth_offset(&Synth, timestamp, (samp[0] - ch->blip_prev_samp[0]) * ch->user_volume / 100, sbuf[0]);
   Blip_Synth_offset(&Synth, timestamp, (samp[1] - ch->blip_prev_samp[1]) * ch->user_volume / 100, sbuf[1]);

   ch->blip_prev_samp[0] = samp[0];
   ch->blip_prev_samp[1] = samp[1];
}

// This function should always be called after RecalcFreqCache() (it's not called from RecalcFreqCache to avoid redundant code)
void PCEFast_PSG::RecalcUOFunc(int chnum)
{
   psg_channel *ch = &channel[chnum];

   if(!(ch->control & 0xC0))
      ch->UpdateOutput = &PCEFast_PSG::UpdateOutput_Off;
   else if(ch->noisectrl & ch->control & 0x80)
      ch->UpdateOutput = &PCEFast_PSG::UpdateOutput_Noise;
   // If the control for the channel is in waveform play mode, and the (real) playback frequency is too high, and the channel is either not the LFO modulator channel or
   // if the LFO trigger bit(which halts the LFO modulator channel's waveform incrementing when set) is clear
   else if((ch->control & 0xC0) == 0x80 && ch->freq_cache <= 0xA && (chnum != 1 || !(lfoctrl & 0x80)) )
      ch->UpdateOutput = &PCEFast_PSG::UpdateOutput_Accum;
   else
      ch->UpdateOutput = &PCEFast_PSG::UpdateOutput_Norm;
}


void PCEFast_PSG::RecalcFreqCache(int chnum)
{
   psg_channel *ch = &channel[chnum];

   if(chnum == 0 && (lfoctrl & 0x03))
   {
      const uint32 shift = (((lfoctrl & 0x3) - 1) << 1);
      uint8 la = channel[1].dda;
      int32 tmp_freq = ((int32)ch->frequency + ((la - 0x10) << shift)) & 0xFFF;

      ch->freq_cache = (tmp_freq ? tmp_freq : 4096) << 1;
   }
   else
   {
      ch->freq_cache = (ch->frequency ? ch->frequency : 4096) << 1;

      if(chnum == 1 && (lfoctrl & 0x03))
         ch->freq_cache *= lfofreq ? lfofreq : 256;
   }
}

void PCEFast_PSG::RecalcNoiseFreqCache(int chnum)
{
   psg_channel *ch = &channel[chnum];
   int32 freq = 0x1F - (ch->noisectrl & 0x1F);

   if(!freq)
      freq = 0x20;
   else
      freq <<= 6;

   freq <<= 1;

   ch->noise_freq_cache = freq;
}

PCEFast_PSG::PCEFast_PSG(Blip_Buffer *bb_l, Blip_Buffer *bb_r)
{
   sbuf[0] = bb_l;
   sbuf[1] = bb_r;

   lastts = 0;
   for(int ch = 0; ch < 6; ch++)
   {
      channel[ch].blip_prev_samp[0] = 0;
      channel[ch].blip_prev_samp[1] = 0;
      channel[ch].lastts = 0;
   }

   SetVolume(1.0);

   for(int vl = 0; vl < 32; vl++)
   {
      double flub = 1;

      if(vl)
         flub /= powf(2, (double)1 / 4 * vl);                  // ~1.5dB reduction per increment of vl 

      if(vl == 0x1F)
         flub = 0;

      for(int samp = 0; samp < 32; samp++)
      {
         int eff_samp = samp * 2 - 0x1F;

         dbtable[vl][samp] = (int32)(flub * eff_samp * 128);
         dbtable_volonly[vl] = (int32)(flub * 65536);
      }
   }

   Power(0);
}

PCEFast_PSG::~PCEFast_PSG()
{


}

int32 PCEFast_PSG::GetVL(const int chnum, const int lr)
{
   // Note: Changing the 0x1F(not that there should be) would require changing the channel pseudo-off volume check logic later on.
   static const uint8 scale_tab[] = 
   {
      0x00, 0x03, 0x05, 0x07, 0x09, 0x0B, 0x0D, 0x0F,
      0x10, 0x13, 0x15, 0x17, 0x19, 0x1B, 0x1D, 0x1F
   };

   psg_channel *ch = &channel[chnum];

   const int gbal = 0x1F - scale_tab[(globalbalance >> (lr ? 0 : 4)) & 0xF];
   const int bal = 0x1F - scale_tab[(ch->balance >> (lr ? 0 : 4)) & 0xF];
   const int al = 0x1F - (ch->control & 0x1F);
   int vol_reduction;

   vol_reduction = gbal + bal + al;

   if(vol_reduction > 0x1F)
      vol_reduction = 0x1F;

   return(vol_reduction);
}

void PCEFast_PSG::Write(int32 timestamp, uint8 A, uint8 V)
{	
   A &= 0x0F;

   if(A == 0x00)
   {
      select = (V & 0x07);
      return;
   }

   Update(timestamp);

   psg_channel *ch = &channel[select];
   
   switch(A)
   {
      default: break;

      case 0x01: /* Global sound balance */
               globalbalance = V;
               vol_pending = true;
               break;

      case 0x02: /* Channel frequency (LSB) */
               if(select > 5) return; // no more than 6 channels, silly game.

               ch->frequency = (ch->frequency & 0x0F00) | V;
               RecalcFreqCache(select);
               RecalcUOFunc(select);
               break;

      case 0x03: /* Channel frequency (MSB) */
               if(select > 5) return; // no more than 6 channels, silly game.

               ch->frequency = (ch->frequency & 0x00FF) | ((V & 0x0F) << 8);
               RecalcFreqCache(select);
               RecalcUOFunc(select);
               break;

      case 0x04: /* Channel enable, DDA, volume */
               if(select > 5) return; // no more than 6 channels, silly game.

               if((ch->control & 0x40) && !(V & 0x40))
               {
                  ch->waveform_index = 0;
                  ch->dda = ch->waveform[ch->waveform_index];
                  ch->counter = ch->freq_cache;
               }

               if(!(ch->control & 0x80) && (V & 0x80)) 
               {
                  if(!(V & 0x40))
                  {
                     ch->waveform_index = (ch->waveform_index + 1) & 0x1F;
                     ch->dda = ch->waveform[ch->waveform_index];
                  }
               }

               ch->control = V;
               RecalcFreqCache(select);
               RecalcUOFunc(select);

               vol_pending = true;
               break;

      case 0x05: /* Channel balance */
               if(select > 5) return; // no more than 6 channels, silly game.
               ch->balance = V;

               vol_pending = true;
               break;

      case 0x06: /* Channel waveform data */
               if(select > 5) return; // no more than 6 channels, silly game.
               V &= 0x1F;

               if(!(ch->control & 0x40))
               {
                  ch->samp_accum -= ch->waveform[ch->waveform_index];
                  ch->waveform[ch->waveform_index] = V;
                  ch->samp_accum += ch->waveform[ch->waveform_index];
               }

               if((ch->control & 0xC0) == 0x00)
                  ch->waveform_index = ((ch->waveform_index + 1) & 0x1F);

               if(ch->control & 0x80)
               {
                  // According to my tests(on SuperGrafx), writing to this channel
                  // will update the waveform value cache/latch regardless of DDA mode being enabled.
                  ch->dda = V;
               }
               break;

      case 0x07: /* Noise enable and frequency */
               if(select > 5) return; // no more than 6 channels, silly game.
               if(select >= 4)
               {
                  ch->noisectrl = V;
                  RecalcNoiseFreqCache(select);
                  RecalcUOFunc(select);
               }
               break;

      case 0x08: /* LFO frequency */
               lfofreq = V & 0xFF;
	       RecalcFreqCache(1);
               break;

      case 0x09: /* LFO trigger and control */
               if(V & 0x80)
               {
                  channel[1].waveform_index = 0;
                  channel[1].dda = channel[1].waveform[channel[1].waveform_index];
                  channel[1].counter = channel[1].freq_cache;
               }
               lfoctrl = V;
               RecalcFreqCache(0);
               RecalcUOFunc(0);
               RecalcFreqCache(1);
               RecalcUOFunc(1);
               break;
   }
}

// Don't use INLINE, which has always_inline in it, due to gcc's inability to cope with the type of recursion
// used in this function.
   template<bool LFO_On>
void PCEFast_PSG::RunChannel(int chc, int32 timestamp)
{
   psg_channel *ch = &channel[chc];
   int32 running_timestamp = ch->lastts;
   int32 run_time = timestamp - ch->lastts;

   ch->lastts = timestamp;
   
   if(!run_time)
      return;

   (this->*ch->UpdateOutput)(running_timestamp, ch);

   if(chc >= 4)
   {
      int32 freq = ch->noise_freq_cache;

      ch->noisecount -= run_time;

#define CLOCK_LFSR(lfsr) { unsigned int newbit = ((lfsr >> 0) ^ (lfsr >> 1) ^ (lfsr >> 11) ^ (lfsr >> 12) ^ (lfsr >> 17)) & 1; lfsr = (lfsr >> 1) | (newbit << 17); }
      if(&PCEFast_PSG::UpdateOutput_Noise == ch->UpdateOutput)
      {
         while(ch->noisecount <= 0)
         {
            CLOCK_LFSR(ch->lfsr);
            UpdateOutput_Noise(timestamp + ch->noisecount, ch);
            ch->noisecount += freq;
         }
      }
      else
      {
         while(ch->noisecount <= 0)
         {
            CLOCK_LFSR(ch->lfsr);
            ch->noisecount += freq;
         }
      }
#undef CLOCK_LFSR
   }

   // D7 of control is 0, don't clock the counter at all.
   // D7 of lfocontrol is 1(and chc == 1), don't clock the counter at all(not sure about this)
   // In DDA mode, don't clock the counter.
   // (Noise being enabled isn't handled here since AFAIK it doesn't disable clocking of the waveform portion, its sound just overrides the sound from
   //  the waveform portion when the noise enable bit is set, which is handled in our RecalcUOFunc).
   if(!(ch->control & 0x80) || (chc == 1 && (lfoctrl & 0x80)) || (ch->control & 0x40))
      return;

   ch->counter -= run_time;

   if(!LFO_On && ch->freq_cache <= 0xA)
   {
      if(ch->counter <= 0)
      {
         const int32 inc_count = ((0 - ch->counter) / ch->freq_cache) + 1;

         ch->counter += inc_count * ch->freq_cache;

         ch->waveform_index = (ch->waveform_index + inc_count) & 0x1F;
         ch->dda = ch->waveform[ch->waveform_index];
      }
   }

   while(ch->counter <= 0)
   {
      ch->waveform_index = (ch->waveform_index + 1) & 0x1F;
      ch->dda = ch->waveform[ch->waveform_index];

      (this->*ch->UpdateOutput)(timestamp + ch->counter, ch);

      if(LFO_On)
      {
         RunChannel<false>(1, timestamp + ch->counter);
         RecalcFreqCache(0);
         RecalcUOFunc(0);

         ch->counter += (ch->freq_cache <= 0xA) ? 0xA : ch->freq_cache;	// Not particularly accurate, but faster.
      }
      else
         ch->counter += ch->freq_cache;
   }
}

INLINE void PCEFast_PSG::UpdateSubLFO(int32 timestamp)
{
   RunChannel<true>(0, timestamp);

   for(int chc = 1; chc < 6; chc++)
      RunChannel<false>(chc, timestamp);
}

INLINE void PCEFast_PSG::UpdateSubNonLFO(int32 timestamp)
{
   for(int chc = 0; chc < 6; chc++)
      RunChannel<false>(chc, timestamp);
}

//static int32 last_read;
//static int32 last_apply;

void PCEFast_PSG::Update(int32 timestamp)
{
   int32 run_time = timestamp - lastts;

   if(vol_pending && !vol_update_counter && !vol_update_which)
   {
      vol_update_counter = 1;
      vol_pending = false;
   }

   bool lfo_on = (bool)(lfoctrl & 0x03);

   if(lfo_on)
   {
      if(!(channel[1].control & 0x80) || (lfoctrl & 0x80))
      {
         lfo_on = 0;
         RecalcFreqCache(0);
         RecalcUOFunc(0);
      }
   }

   int32 clocks = run_time;
   int32 running_timestamp = lastts;

   while(clocks > 0)
   {
      int32 chunk_clocks = clocks;

      if(vol_update_counter > 0 && chunk_clocks > vol_update_counter)
         chunk_clocks = vol_update_counter;

      running_timestamp += chunk_clocks;
      clocks -= chunk_clocks;

      if(lfo_on)
         UpdateSubLFO(running_timestamp);
      else
         UpdateSubNonLFO(running_timestamp);

      if(vol_update_counter > 0)
      {
         vol_update_counter -= chunk_clocks;
         if(!vol_update_counter)
         {
            const int phase = vol_update_which & 1;
            const int lr = ((vol_update_which >> 1) & 1) ^ 1;
            const int chnum = vol_update_which >> 2;

            if(!phase)
            {
               if(chnum < 6)
                  vol_update_vllatch = GetVL(chnum, lr);
            }
            else
            {
               if(chnum < 6)
                  channel[chnum].vl[lr] = vol_update_vllatch;
            }
            vol_update_which = (vol_update_which + 1) & 0x1F;

            if(vol_update_which)
               vol_update_counter = phase ? 1 : 255;
            else if(vol_pending)
            {
               vol_update_counter = phase ? 1 : 255;
               vol_pending = false;
            }
         }
      }

      lastts = running_timestamp;
   }
}

void PCEFast_PSG::EndFrame(int32 timestamp)
{
   Update(timestamp);
   lastts = 0;
   for(int chc = 0; chc < 6; chc++)
      channel[chc].lastts = 0;
}

void PCEFast_PSG::Power(const int32 timestamp)
{
   // Not sure about power-on values, these are mostly just intuitive guesses(with some laziness thrown in).
   if(timestamp != lastts)
      Update(timestamp);

   memset(&channel, 0, sizeof(channel));

   select = 0;
   globalbalance = 0;
   lfofreq = 0;
   lfoctrl = 0;

   for(int ch = 0; ch < 6; ch++)
   {
      channel[ch].frequency = 0;
      channel[ch].control = 0x00;
      channel[ch].balance = 0;
      channel[ch].user_volume = 100;
      memset(channel[ch].waveform, 0, 32);
      channel[ch].samp_accum = 0;

      channel[ch].waveform_index = 0;
      channel[ch].dda = 0x00;
      channel[ch].noisectrl = 0x00;

      channel[ch].vl[0] = 0x1F;
      channel[ch].vl[1] = 0x1F;

      channel[ch].samp_accum = 0;

      RecalcFreqCache(ch);
      RecalcUOFunc(ch);

      channel[ch].counter = channel[ch].freq_cache;

      if(ch >= 4)
      {
         RecalcNoiseFreqCache(ch);
         channel[ch].noisecount = 1;
         channel[ch].lfsr = 1;
      }
   }

   vol_pending = false;
   vol_update_counter = 0;
   vol_update_which = 0;
}

int PCEFast_PSG::StateAction(StateMem *sm, int load, int data_only)
{
   int ret = 1;

   for(int ch = 0; ch < 6; ch++)
   {
      char tmpstr[5] = "SCHx";
      psg_channel *pt = &channel[ch];

      SFORMAT CH_StateRegs[] = 
      {
         SFVARN(pt->counter, "counter"),
         SFVARN(pt->frequency, "frequency"),
         SFVARN(pt->control, "control"),
         SFVARN(pt->balance, "balance"),
         SFARRAYN(pt->waveform, 32, "waveform"),
         SFVARN(pt->waveform_index, "waveform_index"),
         SFVARN(pt->dda, "dda"),
         SFVARN(pt->noisectrl, "noisectrl"),
         SFVARN(pt->noisecount, "noisecount"),
         SFVARN(pt->lfsr, "lfsr"),
         SFARRAY32N(pt->vl, 2, "vl"), // TODO
         SFEND
      };
      tmpstr[3] = '0' + ch;
      ret &= MDFNSS_StateAction(sm, load, data_only, CH_StateRegs, tmpstr, false);
   }

   SFORMAT PSG_StateRegs[] =
   {
      SFVARN(select, "select"),
      SFVARN(globalbalance, "globalbalance"),
      SFVARN(lfofreq, "lfofreq"),
      SFVARN(lfoctrl, "lfoctrl"),

      SFVARN(vol_update_counter, "vol_update_counter"),
      SFVARN(vol_update_which, "vol_update_which"),
      SFVARN(vol_update_vllatch, "vol_update_vllatch"),
      SFVAR_BOOL(vol_pending),
      SFEND
   };

   ret &= MDFNSS_StateAction(sm, load, data_only, PSG_StateRegs, "PSG", false);

   if(load)
   {
      vol_update_which &= 0x1F;

      if(!channel[4].lfsr)
         channel[4].lfsr = 1;

      if(!channel[5].lfsr)
         channel[5].lfsr = 1;

      for(int ch = 0; ch < 6; ch++)
      {
         channel[ch].samp_accum = 0;
         for(int wi = 0; wi < 32; wi++)
         {
            channel[ch].waveform[wi] &= 0x1F;
            channel[ch].samp_accum += channel[ch].waveform[wi];
         }

         for(int lr = 0; lr < 2; lr++)
            channel[ch].vl[lr] &= 0x1F;

         if(!channel[ch].noisecount && ch >= 4)
            channel[ch].noisecount = 1;

         if(channel[ch].counter <= 0)
            channel[ch].counter = 1;

         if(ch >= 4)
            RecalcNoiseFreqCache(ch);
         RecalcFreqCache(ch);
         RecalcUOFunc(ch);
      }
   }
   return(ret); 
}
